Power Conversion Apparatus Harmonic Suppression
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Solution Overview
Problem
Existing power conversion apparatuses face significant efficiency losses due to multiple stages of conversion, and they fail to effectively suppress current harmonic noise, which is essential for reducing environmental impact and conserving energy.
Innovation Solution
A power conversion apparatus that uses a closed-loop circuit with inductors, capacitors, and switches to modulate high-frequency components in synchronization with low-frequency AC power, achieving a sinusoidal current phase and reducing input current harmonics through a control unit that manages gate driving signals for semiconductor switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a power factor improving converter is used to control current to be sinusoidal and in phase with voltage, then current harmonic noise is suppressed, but power loss increases due to current flowing through series diodes and alternating FET/diode switching
Solution Approach 1:
The patent combines the PFC function and AC-DC conversion function into a single integrated circuit stage. The bridge circuit includes four switching elements (Q1-Q4) that perform both current shaping for power factor improvement and voltage rectification simultaneously, eliminating the need for separate PFC and rectification stages. This merging reduces the number of power conversion stages from three to two, thereby reducing cumulative power loss while maintaining sinusoidal current control to suppress harmonic noise.
2Adaptability or versatility
If multiple stages of power conversion are used (AC-DC, DC-DC boost, DC-DC step down), then voltage conversion flexibility is achieved, but overall conversion efficiency significantly decreases due to cumulative losses
Solution Approach 1:
The patent merges the PFC converter and AC-DC converter into a single integrated stage, reducing the total number of conversion stages. The bridge circuit with four switching elements simultaneously performs current shaping, voltage boosting, and rectification functions that were previously distributed across multiple separate stages. This integration maintains voltage conversion flexibility while reducing cumulative efficiency losses from multiple conversion stages.
Solution Approach 2:
The bridge circuit is designed to perform multiple functions simultaneously: it shapes the input current to be sinusoidal (PFC function), boosts the voltage (DC-DC boost function), and rectifies the voltage (AC-DC conversion function). This multi-functionality eliminates the need for separate dedicated circuits for each function, reducing the overall number of stages and improving efficiency while maintaining adaptability.
3Loss of energy
If a bridge circuit with four switching elements is used to perform both PFC and AC-DC conversion, then conversion efficiency improves by reducing stages, but device complexity increases
Solution Approach 1:
The patent integrates multiple conversion functions into a single bridge circuit stage with four switching elements. This merging reduces the overall system complexity by eliminating the need for separate PFC and AC-DC converter stages, even though each switching element must perform multiple functions. The unified structure is simpler than maintaining separate dedicated circuits for each function.
Solution Approach 2:
Each switching element in the bridge circuit is designed to perform multiple functions: current switching for PFC, voltage boosting, and rectification. This multi-functionality reduces the total number of components and circuit stages required, thereby reducing overall device complexity while maintaining high conversion efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances conversion efficiency and suppresses current harmonic noise, resulting in a high-power factor and reduced power loss, making the apparatus more efficient, compact, and cost-effective.
Implementation Method 1
a first inductor L1 and a first capacitor C1 are connected in series to both ends of an AC power supply Vac through a commercial power
Implementation Method 2
a first inductor L1 and a first capacitor C1 are connected in series to both ends of an AC power supply Vac
Implementation Method 3
connecting a third switch S3 and a fourth switch S4 in series, and respectively connecting the first switch and the third switch, and the second switch and the fourth switch. The power conversion circuit connects a series circuit consisting of the first capacitor C1, a second inductor L2, and a primary winding Lp of a transformer T1
Data Source
AI summary
A power conversion apparatus is constituted by a power conversion circuit and a control section. The control section causes a gate driving signal to alternately open and close a set of a first switch and a fourth switch, and a set of a second switch and a third switch based on a circuit current flowing through the power conversion circuit and a voltage of an AC power supply. A current in which a high frequency component is mixed into a low frequency component of the AC power supply flows through the power conversion apparatus by the opening and closing the sets of the switches.